VoLTE optimizations for eMTC devices

ABSTRACT

Aspects of the present disclosure relate to methods and apparatus for optimizing real time services (e.g., such as a voice over Long Term Evolution (LTE) (VoLTE)) for devices with limited communications resources, such as machine type communication (MTC) devices and enhanced MTC (eMTC) devices. In one aspect, a UE determines a first configuration of subframes within at least one radio frame available for the UE and other UEs to use for bundled communications with a BS. The UE receives an indication of one or more subframes within the at least one radio frame that are unavailable for bundled uplink transmissions, and determines a second configuration of subframes to use for bundled communications based on the indication. The UE overrides the first configuration of subframes with the second configuration of subframes, and communicates with the BS using the second configuration of subframes. Numerous other aspects are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Indian Provisional PatentApplication Serial No. 201641025981, filed Jul. 29, 2016, which isassigned to the assignee hereof and hereby expressly incorporated byreference herein.

BACKGROUND I. Field of the Disclosure

Certain aspects of the present disclosure generally relate to wirelesscommunications and more particularly, to methods and apparatus foroptimizing real time services (e.g., such as a voice over Long TermEvolution (LTE) (VoLTE)) for devices with limited communicationsresources, such as machine type communication(s) (MTC) devices andenhanced MTC (eMTC) devices.

II. Description of Related Art

Wireless communication systems are widely deployed to provide varioustelecommunication services such as telephony, video, data, messaging,and broadcasts. Typical wireless communication systems may employmultiple-access technologies capable of supporting communication withmultiple users by sharing available system resources (e.g., bandwidth,transmit power). Examples of such multiple-access technologies includecode division multiple access (CDMA) systems, time division multipleaccess (TDMA) systems, frequency division multiple access (FDMA)systems, 3rd Generation Partnership Project (3GPP) Long Term Evolution(LTE) including LTE-Advanced systems and orthogonal frequency divisionmultiple access (OFDMA) systems.

Generally, a wireless multiple-access communication system cansimultaneously support communication for multiple wireless terminals.Each terminal communicates with one or more base stations viatransmissions on the forward and reverse links. The forward link (ordownlink) refers to the communication link from the base stations to theterminals, and the reverse link (or uplink) refers to the communicationlink from the terminals to the base stations. This communication linkmay be established via a single-input single-output, multiple-inputsingle-output or a multiple-input multiple-output (MIMO) system.

A wireless communication network may include a number of base stationsthat can support communication for a number of wireless devices.Wireless devices may include user equipments (UEs). Some UEs may beconsidered machine type communication (MTC) UEs that may communicatewith a base station, another remote device, or some other entity.Machine type communications (MTC) may refer to communication involvingat least one remote device on at least one end of the communication andmay include forms of communication which involve one or more entitiesthat do not necessarily need human interaction. MTC UEs may include UEsthat are capable of MTC communications with MTC servers and/or other MTCdevices through Public Land Mobile Networks (PLMN), for example.

SUMMARY

The systems, methods, and devices of the disclosure each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this disclosure as expressedby the claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “DETAILED DESCRIPTION” one will understand how thefeatures of this disclosure provide advantages that include improvedcommunications between access points and stations in a wireless network.

The present disclosure relates generally to wireless communication, andmore particularly, to methods and apparatus for optimizing real timeservices (e.g., such as a voice service over long term evolution (LTE)(VoLTE)) for devices with limited communications resources, such as MTCdevices and eMTC devices.

Certain aspects of the present disclosure provide a method for wirelesscommunications performed by a base station (BS). The method generallyincludes determining a first configuration of one or more subframeswithin at least one radio frame available for a plurality of userequipments (UEs) to use for bundled communications with the BS. Themethod also includes determining, for a subset of the plurality of UEs,one or more subframes in the at least one radio frame that areunavailable for bundled uplink transmissions from the subset of UEs. Themethod further includes transmitting an indication of the determinedunavailable subframes to the subset of UEs in order to override thefirst configuration of subframes with a second configuration of one ormore subframes, within the at least one radio frame, for the subset ofUEs to use for bundled communications with the BS. The method furtherincludes communicating with the subset of UEs using the secondconfiguration of subframes.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes at least oneprocessor, and a memory coupled to the at least one processor. The atleast one processor is configured to determine a first configuration ofone or more subframes within at least one radio frame available for aplurality of UEs to use for bundled communications with the apparatus.The at least one processor is also configured to determine, for a subsetof the plurality of UEs, one or more subframes in the at least one radioframe that are unavailable for bundled uplink transmissions from thesubset of UEs. The at least one processor is further configured totransmit an indication of the determined unavailable subframes to thesubset of UEs in order to override the first configuration of subframeswith a second configuration of one or more subframes, within the atleast one radio frame, for the subset of UEs to use for bundledcommunications with the apparatus. The at least one processor is furtherconfigured to communicate with the subset of UEs using the secondconfiguration of subframes.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes means fordetermining a first configuration of one or more subframes within atleast one radio frame available for a plurality of UEs to use forbundled communications with the apparatus. The apparatus also includesmeans for determining, for a subset of the plurality of UEs, one or moresubframes in the at least one radio frame that are unavailable forbundled uplink transmissions from the subset of UEs. The apparatusfurther includes means for transmitting an indication of the determinedunavailable subframes to the subset of UEs in order to override thefirst configuration of subframes with a second configuration of one ormore subframes, within the at least one radio frame, for the subset ofUEs to use for bundled communications with the apparatus. The apparatusfurther includes means for communicating with the subset of UEs usingthe second configuration of subframes.

Certain aspects of the present disclosure provide a computer-readablemedium having computer executable code stored thereon. The computerexecutable code generally includes code for determining, by a BS, afirst configuration of one or more subframes within at least one radioframe available for a plurality of UEs to use for bundled communicationswith the BS. The computer executable code also includes code fordetermining, by the BS for a subset of the plurality of UEs, one or moresubframes in the at least one radio frame that are unavailable forbundled uplink transmissions from the subset of UEs. The computerexecutable code further includes code for transmitting, by the BS, anindication of the determined unavailable subframes to the subset of UEsin order to override the first configuration of subframes with a secondconfiguration of one or more subframes, within the at least one radioframe, for the subset of UEs to use for bundled communications with theBS. The computer executable code further includes code for communicatingby the BS with the subset of UEs using the second configuration ofsubframes.

Certain aspects of the present disclosure provide a method for wirelesscommunications performed by a UE. The method generally includesdetermining a first configuration of one or more subframes within atleast one radio frame available for the UE and one or more other UEs touse for bundled communications with a BS. The method also includesreceiving an indication of one or more subframes within the at least oneradio frame that are unavailable for bundled uplink transmissions by theUE, and determining a second configuration of one or more subframes,within the at least one radio frame, for the UE to use for bundledcommunications with the BS based at least in part on the receivedindication. The method further includes overriding the firstconfiguration of subframes with the second configuration of one or moresubframes, and communicating with the BS using the determined secondconfiguration of subframes.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes at least oneprocessor, and a memory coupled to the at least one processor. The atleast one processor is configured to determine a first configuration ofone or more subframes within at least one radio frame available for theapparatus and one or more other apparatuses to use for bundledcommunications with a BS. The at least one processor is also configuredto receive an indication of one or more subframes within the at leastone radio frame that are unavailable for bundled uplink transmissions bythe apparatus, and determine a second configuration of one or moresubframes, within the at least one radio frame, for the apparatus to usefor bundled communications with the BS based at least in part on thereceived indication. The at least one processor is further configured tooverride the first configuration of subframes with the secondconfiguration of one or more subframes, and communicate with the BSusing the determined second configuration of subframes.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes means fordetermining a first configuration of one or more subframes within atleast one radio frame available for the apparatus and one or more otherapparatuses to use for bundled communications with a BS. The apparatusalso includes means for receiving an indication of one or more subframeswithin the at least one radio frame that are unavailable for bundleduplink transmissions by the apparatus, and means for determining asecond configuration of one or more subframes, within the at least oneradio frame, for the apparatus to use for bundled communications withthe BS based at least in part on the received indication. The apparatusfurther includes means for overriding the first configuration ofsubframes with the second configuration of one or more subframes, andmeans for communicating with the BS using the determined secondconfiguration of subframes.

Certain aspects of the present disclosure provide a computer-readablemedium having computer executable code stored thereon. The computerexecutable code generally includes code for determining, by a UE, afirst configuration of one or more subframes within at least one radioframe available for the UE and one or more other UEs to use for bundledcommunications with a BS. The computer executable code also includescode for receiving, by the UE, an indication of one or more subframeswithin the at least one radio frame that are unavailable for bundleduplink transmissions by the UE, and code for determining, by the UE, asecond configuration of one or more subframes, within the at least oneradio frame, for the UE to use for bundled communications with the BSbased at least in part on the received indication. The computerexecutable code further includes code for overriding, by the UE, thefirst configuration of subframes with the second configuration of one ormore subframes, and code for communicating, by the UE, with the BS usingthe determined second configuration of subframes.

Certain aspects of the present disclosure provide a method for wirelesscommunications performed by a BS. The method generally includesdetermining, for communications with a subset of a plurality of UEs, agrant that schedules one or more bundled downlink transmissions from theBS and one or more bundled uplink transmissions from the subset of UEs.The method also includes transmitting the grant to the subset of UEs inone subframe of a plurality of subframes within at least one radioframe. The method further includes communicating with the subset of UEsbased at least in part on the grant.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes at least oneprocessor, and a memory coupled to the at least one processor. The atleast one processor is configured to determine, for communications witha subset of a plurality of UEs, a grant that schedules one or morebundled downlink transmissions from the apparatus and one or morebundled uplink transmissions from the subset of UEs. The at least oneprocessor is also configured to transmit the grant to the subset of UEsin one subframe of a plurality of subframes within at least one radioframe. The at least one processor is further configured to communicatewith the subset of UEs based at least in part on the grant.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes means fordetermining, for communications with a subset of a plurality of UEs, agrant that schedules one or more bundled downlink transmissions from theapparatus and one or more bundled uplink transmissions from the subsetof UEs. The apparatus also includes means for transmitting the grant tothe subset of UEs in one subframe of a plurality of subframes within atleast one radio frame. The apparatus further includes means forcommunicating with the subset of UEs based at least in part on thegrant.

Certain aspects of the present disclosure provide a computer-readablemedium having computer executable code stored thereon. The computerexecutable code generally includes code for determining, by a BS forcommunications with a subset of a plurality of UEs, a grant thatschedules one or more bundled downlink transmissions from the BS and oneor more bundled uplink transmissions from the subset of UEs. Thecomputer executable code also includes code for transmitting, by the BS,the grant to the subset of UEs in one subframe of a plurality ofsubframes within at least one radio frame. The computer executable codefurther includes code for communicating, by the BS, with the subset ofUEs based at least in part on the grant.

Certain aspects of the present disclosure provide a method for wirelesscommunications performed by a UE. The method generally includesreceiving, for communications with a BS, in one subframe of a pluralityof subframes within at least one radio frame, a grant for bundleddownlink transmissions from the BS and bundled uplink transmissions fromthe UE. The method further includes communicating with the BS based onthe received grant.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes at least oneprocessor, and a memory coupled to the at least one processor. The atleast one processor is configured to receive, for communications with aBS, in one subframe of a plurality of subframes within at least oneradio frame, a grant for bundled downlink transmissions from the BS andbundled uplink transmissions from the apparatus. The at least oneprocessor is further configured to communicate with the BS based on thereceived grant.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes means forreceiving, for communications with a BS, in one subframe of a pluralityof subframes within at least one radio frame, a grant for bundleddownlink transmissions from the BS and bundled uplink transmissions fromthe apparatus. The apparatus further includes means for communicatingwith the BS based on the received grant.

Certain aspects of the present disclosure provide a computer-readablemedium having computer executable code stored thereon. The computerexecutable code generally includes code for receiving, by a UE forcommunications with a BS, in one subframe of a plurality of subframeswithin at least one radio frame, a grant for bundled downlinktransmissions from the BS and bundled uplink transmissions from the UE.The computer executable code further includes code for communicating, bythe UE, with the BS based on the received grant.

Certain aspects of the present disclosure provide a method for wirelesscommunications performed by a BS. The method generally includesreceiving, during communications with a UE, one or more bundled uplinktransmissions from the UE without a silence insertion descriptor (SID)frame. The method further includes determining whether the bundleduplink transmissions include a physical uplink control channel (PUCCH)transmitted from the UE. The method further includes deciding whether tocontinue communicating with the UE based on the determination.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes at least oneprocessor, and a memory coupled to the at least one processor. The atleast one processor is configured to receive, during communications witha UE, one or more bundled uplink transmissions from the UE without asilence insertion descriptor (SID) frame. The at least one processor isfurther configured to determine whether the bundled uplink transmissionsinclude a physical uplink control channel (PUCCH) transmitted from theUE. The at least one processor is further configured to decide whetherto continue communicating with the UE based on the determination.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes means forreceiving, during communications with a UE, one or more bundled uplinktransmissions from the UE without a silence insertion descriptor (SID)frame. The apparatus further includes means for determining whether thebundled uplink transmissions include a physical uplink control channel(PUCCH) transmitted from the UE. The apparatus further includes meansfor deciding whether to continue communicating with the UE based on thedetermination.

Certain aspects of the present disclosure provide a computer-readablemedium having computer executable code stored thereon. The computerexecutable code generally includes code for receiving, by a BS duringcommunications with a UE, one or more bundled uplink transmissions fromthe UE without a silence insertion descriptor (SID) frame. The computerexecutable code further includes code for determining, by the BS,whether the bundled uplink transmissions include a physical uplinkcontrol channel (PUCCH) transmitted from the UE. The computer executablecode further includes code for deciding, by the BS, whether to continuecommunicating with the UE based on the determination.

Certain aspects of the present disclosure provide a method for wirelesscommunications performed by a UE. The method generally includestransmitting, during communications with a BS, one or more bundleduplink transmissions to the BS without a silence insertion descriptor(SID) frame. The method further includes transmitting a physical uplinkcontrol channel (PUCCH) within the bundled uplink transmissions toindicate that the UE is connected to the BS via the communications.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes at least oneprocessor, and a memory coupled to the at least one processor. The atleast one processor is configured to transmit, during communicationswith a BS, one or more bundled uplink transmissions to the BS without asilence insertion descriptor (SID) frame. The at least one processor isfurther configured to transmit a physical uplink control channel (PUCCH)within the bundled uplink transmissions to indicate that the apparatusis connected to the BS via the communications.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes means fortransmitting, during communications with a BS, one or more bundleduplink transmissions to the BS without a silence insertion descriptor(SID) frame. The apparatus further includes means for transmitting aphysical uplink control channel (PUCCH) within the bundled uplinktransmissions to indicate that the apparatus is connected to the BS viathe communications.

Certain aspects of the present disclosure provide a computer-readablemedium having computer executable code stored thereon. The computerexecutable code generally includes code for transmitting, by a UE duringcommunications with a BS, one or more bundled uplink transmissions tothe BS without a silence insertion descriptor (SID) frame. The computerexecutable code further includes code for transmitting, by the UE, aphysical uplink control channel (PUCCH) within the bundled uplinktransmissions to indicate that the UE is connected to the BS via thecommunications.

Other aspects, features, and aspects of the present disclosure willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific, exemplary aspects of the presentdisclosure in conjunction with the accompanying figures. While featuresof the present disclosure may be discussed relative to certain aspectsand figures below, all aspects of the present disclosure can include oneor more of the advantageous features discussed herein. In other words,while one or more aspects may be discussed as having certainadvantageous features, one or more of such features may also be used inaccordance with the various aspects of the invention disclosure herein.In similar fashion, while exemplary aspects may be discussed below asdevice, system, or method aspects it should be understood that suchexemplary aspects can be implemented in various devices, systems,methods, and computer readable media.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the appended drawings. The appended drawingsillustrate only certain typical aspects of this disclosure, however, andare therefore not to be considered limiting of its scope, for thedescription may admit to other equally effective aspects.

FIG. 1 is a diagram illustrating an example of a network architecture,in accordance with certain aspects of the disclosure.

FIG. 2 is a diagram illustrating an example of an access network, inaccordance with certain aspects of the disclosure.

FIG. 3 is a diagram illustrating an example of a downlink framestructure in long term evolution (LTE), in accordance with certainaspects of the disclosure.

FIG. 4 is a diagram illustrating an example of an uplink frame structurein LTE, in accordance with certain aspects of the disclosure.

FIG. 5 is a diagram illustrating an example of a radio protocolarchitecture for the user and control plane, in accordance with certainaspects of the disclosure.

FIG. 6 is a diagram illustrating an example of an evolved Node B (eNB)and user equipment (UE) in an access network, in accordance with certainaspects of the disclosure.

FIGS. 7A and 7B illustrate an example of MTC co-existence within awideband system, such as LTE, in accordance with certain aspects of thepresent disclosure.

FIG. 8A illustrates an example of different states for a VoLTE call, inaccordance with certain aspects of the present disclosure.

FIG. 8B illustrates an example exchange of voice and silence frames fora VoLTE call, in accordance with certain aspects of the presentdisclosure.

FIG. 9 illustrates an example timeline for a UE for a portion of a VoLTEcall, in accordance with certain aspects of the present disclosure.

FIG. 10 is a flow diagram illustrating example operations for wirelesscommunications by a base station (BS), in accordance with certainaspects of the present disclosure.

FIG. 11 is a flow diagram illustrating example operations for wirelesscommunications by a user equipment (UE), in accordance with certainaspects of the present disclosure.

FIG. 12 illustrates an example of a UE overriding a cell-specificsubframe configuration with a UE-specific subframe configuration, inaccordance with certain aspects of the present disclosure.

FIG. 13 is a flow diagram illustrating example operations for wirelesscommunications by a BS, in accordance with certain aspects of thepresent disclosure.

FIG. 14 is a flow diagram illustrating example operations for wirelesscommunications by a UE, in accordance with certain aspects of thepresent disclosure.

FIG. 15 illustrates an example of a “joint grant” that schedules PDSCHand PUSCH at the same time, in accordance with certain aspects of thepresent disclosure.

FIG. 16 is a flow diagram illustrating example operations for wirelesscommunications by a BS, in accordance with certain aspects of thepresent disclosure.

FIG. 17 is a flow diagram illustrating example operations for wirelesscommunications by a UE, in accordance with certain aspects of thepresent disclosure.

FIG. 18 illustrates an example of a delayed SID frame delivery for aVoLTE call, in accordance with certain aspects of the presentdisclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in one aspectmay be beneficially utilized on other aspects without specificrecitation.

DETAILED DESCRIPTION

Aspects of the present disclosure discuss techniques for optimizing realtime services (e.g., such as a voice service over long term evolution(LTE) (VoLTE)) for devices with limited communications resources, suchas MTC devices and eMTC devices.

According to certain aspects, a BS may determine a first subframeconfiguration for UEs to use for bundled communications with the BS.Such subframe configuration, for example, may be a cell-specificconfiguration that is supported by different types of UEs (e.g., legacyUEs, advanced UEs, MTC UEs, etc.) in the network, and may specify whichsubframes in one or more radio frames are available (or valid) foruplink transmissions by the UEs and which subframes in the one or moreradio frames are available for monitoring for downlink transmissionsfrom the BS. The BS may determine, for a subset of UEs in the network,one or more subframes that are unavailable (or not valid) for bundleduplink transmissions from the subset of UEs. The BS may transmit anindication of the determined unavailable subframes to the subset of UEs.

The subset of UEs may determine a second subframe configuration for thesubset of UEs to use for bundled communications with the BS based atleast in part on the received indication. The subset of UEs may overridethe first subframe configuration with the second subframe configuration.The BS and the subset of UEs may then communicate using the secondsubframe configuration. In one example, the communication may includeparticipating in a real time service (e.g., such as VoLTE call) usingthe second subframe configuration.

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and should not be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein one skilled in the art should appreciate that the scopeof the disclosure is intended to cover any aspect of the disclosuredisclosed herein, whether implemented independently of or combined withany other aspect of the disclosure. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition toor other than the various aspects of the disclosure set forth herein. Itshould be understood that any aspect of the disclosure disclosed hereinmay be embodied by one or more elements of a claim. The word “exemplary”is used herein to mean “serving as an example, instance, orillustration.” Any aspect described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otheraspect. Several aspects of telecommunication systems will now bepresented with reference to various apparatus and methods. Theseapparatus and methods will be described in the following detaileddescription and illustrated in the accompanying drawings by variousblocks, modules, components, circuits, steps, processes, algorithms,etc. (collectively referred to as “elements”). These elements may beimplemented using hardware, software, or combinations thereof. Whethersuch elements are implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem.

An access point (“AP”) may comprise, be implemented as, or known asNodeB, Radio Network Controller (“RNC”), eNodeB (eNB), Base StationController (“BSC”), Base Transceiver Station (“BTS”), Base Station(“BS”), Transceiver Function (“TF”), Radio Router, Radio Transceiver,Basic Service Set (“BSS”), Extended Service Set (“ESS”), Radio BaseStation (“RBS”), or some other terminology.

An access terminal (“AT”) may comprise, be implemented as, or be knownas an access terminal, a subscriber station, a subscriber unit, a mobilestation, a remote station, a remote terminal, a user terminal, a useragent, a user device, user equipment (UE), a user station, a wirelessnode, or some other terminology. In some implementations, an UE maycomprise a cellular telephone, a smart phone, a cordless telephone, aSession Initiation Protocol (“SIP”) phone, a wireless local loop (“WLL”)station, wireless modems, a personal digital assistant (“PDA”), atablet, a netbook, a smartbook, an ultrabook, a handheld device havingwireless connection capability, a Station (“STA”), or some othersuitable processing device connected to a wireless modem. Accordingly,one or more aspects taught herein may be incorporated into a phone(e.g., a cellular phone, a smart phone), a computer (e.g., a desktop), aportable communication device, a portable computing device (e.g., alaptop, a personal data assistant, a tablet, a netbook, a smartbook, anultrabook), wearable device (e.g., smart watch, smart glasses, virtualreality goggles, smart bracelet, smart wristband, smart ring, smartclothing, etc.), medical devices or equipment, healthcare device orequipment, biometric sensors/devices, an entertainment device (e.g.,music device, video device, satellite radio, gaming device, etc.), adrone, a robot/robotic device, a vehicular component or sensor, smartmeters/sensors, industrial manufacturing equipment, a positioning orposition location device, or any other suitable device that isconfigured to communicate via a wireless or wired medium. In someaspects, the node is a wireless node. A wireless node may provide, forexample, connectivity for or to a network (e.g., a wide area networksuch as the Internet or a cellular network) via a wired or wirelesscommunication link. Some UEs may be considered machine-typecommunication (MTC) UEs, which may include remote devices that maycommunicate with a base station, another remote device, or some otherentity. Machine type communications (MTC) may refer to communicationinvolving at least one remote device on at least one end of thecommunication and may include forms of data communication which involveone or more entities that do not necessarily need human interaction. Toenhance coverage of certain devices, such as MTC devices, “bundling” maybe utilized in which certain transmissions are sent as a bundle oftransmissions, for example, with the same information transmitted overmultiple subframes. MTC UEs may include UEs that are capable of MTCcommunications with MTC servers and/or other MTC devices through PublicLand Mobile Networks (PLMN), for example. Examples of MTC devicesinclude sensors, meters, location tags, monitors, trackers, drones,robots/robotic devices, etc. MTC type UEs, as well as other types ofUEs, may be implemented as NB-IoT (narrowband internet of things)devices.

It is noted that while aspects may be described herein using terminologycommonly associated with 3G and/or 4G wireless technologies, aspects ofthe present disclosure can be applied in other generation-basedcommunication systems, such as 5G and later.

FIG. 1 is a diagram illustrating a network architecture 100 in whichaspects of the present disclosure may be practiced. For example, the UE102 can establish a connection with eNB 106 in order to participate in areal time service with eNB 106. Such real time service, for example, canbe a voice call that is delivered over IP via an LTE access network 104(e.g., VoLTE call), video service delivered over an LTE access network104, etc. As described in more detail below, such real time service canbe optimized using one or more techniques described herein.

The LTE network architecture 100 may be referred to as an Evolved PacketSystem (EPS) 100. The EPS 100 may include one or more user equipment(UE) 102, an Evolved UMTS Terrestrial Radio Access Network (E-UTRAN)104, an Evolved Packet Core (EPC) 110, a Home Subscriber Server (HSS)120, and an Operator's IP Services 122. The EPS can interconnect withother access networks, as shown in FIG. 1A. Exemplary other accessnetworks may include an IP Multimedia Subsystem (IMS) PDN, Internet PDN,Administrative PDN (e.g., Provisioning PDN), carrier-specific PDN,operator-specific PDN, and/or GPS PDN. In aspects, an exemplary accessnetwork may include an access network for VoIP Voice Traffic. The EPS100 provides packet-switched services, however, as those skilled in theart will readily appreciate, the various concepts presented throughoutthis disclosure may be extended to networks providing circuit-switchedservices.

The E-UTRAN includes the evolved Node B (eNB) 106 and other eNBs 108.The eNB 106 provides user and control plane protocol terminations towardthe UE 102. The eNB 106 may be connected to the other eNBs 108 via an X2interface (e.g., backhaul). The eNB 106 may also be referred to as abase station, a base transceiver station, a radio base station, a radiotransceiver, a transceiver function, a basic service set (BSS), anextended service set (ESS), an access point, or some other suitableterminology. The eNB 106 may provide an access point to the EPC 110 fora UE 102. Examples of UEs 102 include a cellular phone, a smart phone, asession initiation protocol (SIP) phone, a laptop, a personal digitalassistant (PDA), a satellite radio, a global positioning system, amultimedia device, a video device, a digital audio player (e.g., MP3player), a camera, a game console, a tablet, a netbook, a smart book, anultrabook, a drone, a robot, a sensor, a monitor, a meter, or any othersimilar functioning device. The UE 102 may also be referred to by thoseskilled in the art as a mobile station, a subscriber station, a mobileunit, a subscriber unit, a wireless unit, a remote unit, a mobiledevice, a wireless device, a wireless communications device, a remotedevice, a mobile subscriber station, an access terminal, a mobileterminal, a wireless terminal, a remote terminal, a handset, a useragent, a mobile client, a client, or some other suitable terminology.

The eNB 106 is connected by an S1 interface to the EPC 110. The EPC 110includes a Mobility Management Entity (MME) 112, other MMEs 114, aServing Gateway 116, and a Packet Data Network (PDN) Gateway 118. TheMME 112 is the control node that processes the signaling between the UE102 and the EPC 110. Generally, the MME 112 provides bearer andconnection management. All user IP packets are transferred through theServing Gateway 116, which itself is connected to the PDN Gateway 118.The PDN Gateway 118 provides UE IP address allocation as well as otherfunctions. The PDN Gateway 118 is connected to the Operator's IPServices 122. The Operator's IP Services 122 may include, for example,the Internet, the Intranet, an IP Multimedia Subsystem (IMS), and a PS(packet-switched) Streaming Service (PSS). In this manner, the UE 102may be coupled to the PDN through the LTE network.

One or more UEs 102 in EPS 100 may also be low cost (LC), low data ratedevices, e.g., such as LC MTC UEs, LC eMTC UEs, etc. The LC UEs mayco-exist with legacy and/or advanced UEs in the LTE network and may haveone or more capabilities that are limited when compared to the other UEs(e.g., non-LC UEs) in the wireless network. For example, when comparedto legacy and/or advanced UEs in the LTE network, the LC UEs may operatewith one or more of the following: a reduction in maximum bandwidth(relative to legacy UEs), a single receive radio frequency (RF) chain,reduction of peak rate, reduction of transmit power, rank 1transmission, half duplex operation, etc. As used herein, devices withlimited communication resources, such as MTC devices, eMTC devices, etc.are referred to generally as LC UEs. Similarly, legacy devices, such aslegacy and/or advanced UEs (e.g., in LTE) are referred to generally asnon-LC UEs.

FIG. 2 is a diagram illustrating an example of an access network 200 inan LTE network architecture in which aspects of the present disclosuremay be practiced. For example, devices such as eNB 106 and/or LC UEs(e.g., UE 102) can be configured to implement techniques that optimizereal time services, such as VoLTE.

In this example, the access network 200 is divided into a number ofcellular regions (cells) 202. One or more lower power class eNBs 208 mayhave cellular regions 210 that overlap with one or more of the cells202. A lower power class eNB 208 may be referred to as a remote radiohead (RRH). The lower power class eNB 208 may be a femto cell (e.g.,home eNB (HeNB)), pico cell, or micro cell. The macro eNBs 204 are eachassigned to a respective cell 202 and are configured to provide anaccess point to the EPC 110 for all the UEs 206 in the cells 202. Thereis no centralized controller in this example of an access network 200,but a centralized controller may be used in alternative configurations.The eNBs 204 are responsible for all radio related functions includingbearer control, admission control, mobility control, scheduling,security, and connectivity to the serving gateway 116. The network 200may also include one or more relays (not shown). According to oneapplication, a UE may serve as a relay.

The modulation and multiple access scheme employed by the access network200 may vary depending on the particular telecommunications standardbeing deployed. In LTE applications, OFDM is used on the DL and SC-FDMAis used on the UL to support both frequency division duplexing (FDD) andtime division duplexing (TDD). As those skilled in the art will readilyappreciate from the detailed description to follow, the various conceptspresented herein are well suited for LTE applications. However, theseconcepts may be readily extended to other telecommunication standardsemploying other modulation and multiple access techniques. By way ofexample, these concepts may be extended to Evolution-Data Optimized(EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interfacestandards promulgated by the 3rd Generation Partnership Project 2(3GPP2) as part of the CDMA2000 family of standards and employs CDMA toprovide broadband Internet access to mobile stations. These concepts mayalso be extended to Universal Terrestrial Radio Access (UTRA) employingWideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA;Global System for Mobile Communications (GSM) employing TDMA; andEvolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM employingOFDMA. UTRA, E-UTRA, UMTS, LTE and GSM are described in documents fromthe 3GPP organization. CDMA2000 and UMB are described in documents fromthe 3GPP2 organization. The actual wireless communication standard andthe multiple access technology employed will depend on the specificapplication and the overall design constraints imposed on the system.

The eNBs 204 may have multiple antennas supporting MIMO technology. Theuse of MIMO technology enables the eNBs 204 to exploit the spatialdomain to support spatial multiplexing, beamforming, and transmitdiversity. Spatial multiplexing may be used to transmit differentstreams of data simultaneously on the same frequency. The data streamsmay be transmitted to a single UE 206 to increase the data rate or tomultiple UEs 206 to increase the overall system capacity. This isachieved by spatially precoding each data stream (e.g., applying ascaling of an amplitude and a phase) and then transmitting eachspatially precoded stream through multiple transmit antennas on the DL.The spatially precoded data streams arrive at the UE(s) 206 withdifferent spatial signatures, which enables each of the UE(s) 206 torecover the one or more data streams destined for that UE 206. On theUL, each UE 206 transmits a spatially precoded data stream, whichenables the eNB 204 to identify the source of each spatially precodeddata stream.

Spatial multiplexing is generally used when channel conditions are good.When channel conditions are less favorable, beamforming may be used tofocus the transmission energy in one or more directions. This may beachieved by spatially precoding the data for transmission throughmultiple antennas. To achieve good coverage at the edges of the cell, asingle stream beamforming transmission may be used in combination withtransmit diversity.

In the detailed description that follows, various aspects of an accessnetwork will be described with reference to a MIMO system supportingOFDM on the DL. OFDM is a spread-spectrum technique that modulates dataover a number of subcarriers within an OFDM symbol. The subcarriers arespaced apart at precise frequencies. The spacing provides“orthogonality” that enables a receiver to recover the data from thesubcarriers. In the time domain, a guard interval (e.g., cyclic prefix)may be added to each OFDM symbol to combat inter-OFDM-symbolinterference. The UL may use SC-FDMA in the form of a DFT-spread OFDMsignal to compensate for high peak-to-average power ratio (PAPR).

FIG. 3 is a diagram 300 illustrating an example of a DL frame structurein LTE. A frame (10 ms) may be divided into 10 equally sized sub-frameswith indices of 0 through 9. Each sub-frame may include two consecutivetime slots. A resource grid may be used to represent two time slots,each time slot including a resource block. The resource grid is dividedinto multiple resource elements. In LTE, a resource block contains 12consecutive subcarriers in the frequency domain and, for a normal cyclicprefix in each OFDM symbol, 7 consecutive OFDM symbols in the timedomain, or 84 resource elements. For an extended cyclic prefix, aresource block contains 6 consecutive OFDM symbols in the time domainand has 72 resource elements. Some of the resource elements, asindicated as R 302, R 304, include DL reference signals (DL-RS). TheDL-RS include Cell-specific RS (CRS) (also sometimes called common RS)302 and UE-specific RS (UE-RS) 304. UE-RS 304 are transmitted only onthe resource blocks upon which the corresponding physical DL sharedchannel (PDSCH) is mapped. The number of bits carried by each resourceelement depends on the modulation scheme. Thus, the more resource blocksthat a UE receives and the higher the modulation scheme, the higher thedata rate for the UE.

In LTE, an eNB may send a primary synchronization signal (PSS) and asecondary synchronization signal (SSS) for each cell in the eNB. Theprimary and secondary synchronization signals may be sent in symbolperiods 6 and 5, respectively, in each of subframes 0 and 5 of eachradio frame with the normal cyclic prefix (CP). The synchronizationsignals may be used by UEs for cell detection and acquisition. The eNBmay send a Physical Broadcast Channel (PBCH) in symbol periods 0 to 3 inslot 1 of subframe 0. The PBCH may carry certain system information.

The eNB may send a Physical Control Format Indicator Channel (PCFICH) inthe first symbol period of each subframe. The PCFICH may convey thenumber of symbol periods (M) used for control channels, where M may beequal to 1, 2 or 3 and may change from subframe to subframe. M may alsobe equal to 4 for a small system bandwidth, e.g., with less than 10resource blocks. The eNB may send a Physical HARQ Indicator Channel(PHICH) and a Physical Downlink Control Channel (PDCCH) in the first Msymbol periods of each subframe. The PHICH may carry information tosupport hybrid automatic repeat request (HARQ). The PDCCH may carryinformation on resource allocation for UEs and control information fordownlink channels. The eNB may send a Physical Downlink Shared Channel(PDSCH) in the remaining symbol periods of each subframe. The PDSCH maycarry data for UEs scheduled for data transmission on the downlink.

The eNB may send the PSS, SSS, and PBCH in the center 1.08 MHz of thesystem bandwidth used by the eNB. The eNB may send the PCFICH and PHICHacross the entire system bandwidth in each symbol period in which thesechannels are sent. The eNB may send the PDCCH to groups of UEs incertain portions of the system bandwidth. The eNB may send the PDSCH tospecific UEs in specific portions of the system bandwidth. The eNB maysend the PSS, SSS, PBCH, PCFICH, and PHICH in a broadcast manner to allUEs, may send the PDCCH in a unicast manner to specific UEs, and mayalso send the PDSCH in a unicast manner to specific UEs.

A number of resource elements may be available in each symbol period.Each resource element (RE) may cover one subcarrier in one symbol periodand may be used to send one modulation symbol, which may be a real orcomplex value. Resource elements not used for a reference signal in eachsymbol period may be arranged into resource element groups (REGs). EachREG may include four resource elements in one symbol period. The PCFICHmay occupy four REGs, which may be spaced approximately equally acrossfrequency, in symbol period 0. The PHICH may occupy three REGs, whichmay be spread across frequency, in one or more configurable symbolperiods. For example, the three REGs for the PHICH may all belong insymbol period 0 or may be spread in symbol periods 0, 1, and 2. ThePDCCH may occupy 9, 18, 36, or 72 REGs, which may be selected from theavailable REGs, in the first M symbol periods, for example. Only certaincombinations of REGs may be allowed for the PDCCH. In aspects of thepresent methods and apparatus, a subframe may include more than onePDCCH.

A UE may know the specific REGs used for the PHICH and the PCFICH. TheUE may search different combinations of REGs for the PDCCH. The numberof combinations to search is typically less than the number of allowedcombinations for the PDCCH. An eNB may send the PDCCH to the UE in anyof the combinations that the UE will search.

FIG. 4 is a diagram 400 illustrating an example of an UL frame structurein LTE. The available resource blocks for the UL may be partitioned intoa data section and a control section. The control section may be formedat the two edges of the system bandwidth and may have a configurablesize. The resource blocks in the control section may be assigned to UEsfor transmission of control information. The data section may includeall resource blocks not included in the control section. The UL framestructure results in the data section including contiguous subcarriers,which may allow a single UE to be assigned all of the contiguoussubcarriers in the data section.

A UE may be assigned resource blocks 410 a, 410 b in the control sectionto transmit control information to an eNB. The UE may also be assignedresource blocks 420 a, 420 b in the data section to transmit data to theeNB. The UE may transmit control information in a physical UL controlchannel (PUCCH) on the assigned resource blocks in the control section.The UE may transmit only data or both data and control information in aphysical UL shared channel (PUSCH) on the assigned resource blocks inthe data section. A UL transmission may span both slots of a subframeand may hop across frequency.

A set of resource blocks may be used to perform initial system accessand achieve UL synchronization in a physical random access channel(PRACH) 430. The PRACH 430 carries a random sequence and cannot carryany UL data/signaling. Each random access preamble occupies a bandwidthcorresponding to six consecutive resource blocks. The starting frequencyis specified by the network. That is, the transmission of the randomaccess preamble is restricted to certain time and frequency resources.There is no frequency hopping for the PRACH. The PRACH attempt iscarried in a single subframe (1 ms) or in a sequence of few contiguoussubframes and a UE can make only a single PRACH attempt per frame (10ms).

FIG. 5 is a diagram 500 illustrating an example of a radio protocolarchitecture for the user and control planes in LTE. The radio protocolarchitecture for the UE and the eNB is shown with three layers: Layer 1,Layer 2, and Layer 3. Layer 1 (L1 layer) is the lowest layer andimplements various physical layer signal processing functions. The L1layer will be referred to herein as the physical layer 506. Layer 2 (L2layer) 508 is above the physical layer 506 and is responsible for thelink between the UE and eNB over the physical layer 506.

In the user plane, the L2 layer 508 includes a media access control(MAC) sublayer 510, a radio link control (RLC) sublayer 512, and apacket data convergence protocol (PDCP) 514 sublayer, which areterminated at the eNB on the network side. Although not shown, the UEmay have several upper layers above the L2 layer 508 including a networklayer (e.g., IP layer) that is terminated at the PDN gateway 118 on thenetwork side, and an application layer that is terminated at the otherend of the connection (e.g., far end UE, server, etc.).

The PDCP sublayer 514 provides multiplexing between different bearersand logical channels. The PDCP sublayer 514 also provides headercompression for upper layer data packets to reduce radio transmissionoverhead, security by ciphering the data packets, and handover supportfor UEs between eNBs. The RLC sublayer 512 provides segmentation andreassembly of upper layer data packets, retransmission of lost datapackets, and reordering of data packets to compensate for out-of-orderreception due to hybrid automatic repeat request (HARQ). The MACsublayer 510 provides multiplexing between logical and transportchannels. The MAC sublayer 510 is also responsible for allocating thevarious radio resources (e.g., resource blocks) in one cell among theUEs. The MAC sublayer 510 is also responsible for HARQ operations.

In the control plane, the radio protocol architecture for the UE and eNBis substantially the same for the physical layer 506 and the L2 layer508 with the exception that there is no header compression function forthe control plane. The control plane also includes a radio resourcecontrol (RRC) sublayer 516 in Layer 3 (L3 layer). The RRC sublayer 516is responsible for obtaining radio resources (e.g., radio bearers) andfor configuring the lower layers using RRC signaling between the eNB andthe UE.

FIG. 6 is a block diagram of an eNB 610 in communication with a UE 650in an access network, in which aspects of the present disclosure may bepracticed.

In the DL, upper layer packets from the core network are provided to acontroller/processor 675. The controller/processor 675 implements thefunctionality of the L2 layer. In the DL, the controller/processor 675provides header compression, ciphering, packet segmentation andreordering, multiplexing between logical and transport channels, andradio resource allocations to the UE 650 based on various prioritymetrics. The controller/processor 675 is also responsible for HARQoperations, retransmission of lost packets, and signaling to the UE 650.

The TX processor 616 implements various signal processing functions forthe L1 layer (physical layer). The signal processing functions includescoding and interleaving to facilitate forward error correction (FEC) atthe UE 650 and mapping to signal constellations based on variousmodulation schemes (e.g., binary phase-shift keying (BPSK), quadraturephase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadratureamplitude modulation (M-QAM)). The coded and modulated symbols are thensplit into parallel streams. Each stream is then mapped to an OFDMsubcarrier, multiplexed with a reference signal (e.g., pilot) in thetime and/or frequency domain, and then combined together using anInverse Fast Fourier Transform (IFFT) to produce a physical channelcarrying a time domain OFDM symbol stream. The OFDM stream is spatiallyprecoded to produce multiple spatial streams. Channel estimates from achannel estimator 674 may be used to determine the coding and modulationscheme, as well as for spatial processing. The channel estimate may bederived from a reference signal and/or channel condition feedbacktransmitted by the UE 650. Each spatial stream is then provided to adifferent antenna 620 via a separate transmitter 618TX. Each transmitter618TX modulates an RF carrier with a respective spatial stream fortransmission.

At the UE 650, each receiver 654RX receives a signal through itsrespective antenna 652. Each receiver 654RX recovers informationmodulated onto an RF carrier and provides the information to thereceiver (RX) processor 656. The RX processor 656 implements varioussignal processing functions of the L1 layer. The RX processor 656performs spatial processing on the information to recover any spatialstreams destined for the UE 650. If multiple spatial streams aredestined for the UE 650, they may be combined by the RX processor 656into a single OFDM symbol stream. The RX processor 656 then converts theOFDM symbol stream from the time-domain to the frequency domain using aFast Fourier Transform (FFT). The frequency domain signal comprises aseparate OFDM symbol stream for each subcarrier of the OFDM signal. Thesymbols on each subcarrier, and the reference signal, is recovered anddemodulated by determining the most likely signal constellation pointstransmitted by the eNB 610. These soft decisions may be based on channelestimates computed by the channel estimator 658. The soft decisions arethen decoded and deinterleaved to recover the data and control signalsthat were originally transmitted by the eNB 610 on the physical channel.The data and control signals are then provided to thecontroller/processor 659.

The controller/processor 659 implements the L2 layer. Thecontroller/processor can be associated with a memory 660 that storesprogram codes and data. The memory 660 may be referred to as acomputer-readable medium. In the UL, the controller/processor 659provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the core network. The upper layerpackets are then provided to a data sink 662, which represents all theprotocol layers above the L2 layer. Various control signals may also beprovided to the data sink 662 for L3 processing. Thecontroller/processor 659 is also responsible for error detection usingan acknowledgement (ACK) and/or negative acknowledgement (NACK) protocolto support HARQ operations.

In the UL, a data source 667 is used to provide upper layer packets tothe controller/processor 659. The data source 667 represents allprotocol layers above the L2 layer. Similar to the functionalitydescribed in connection with the DL transmission by the eNB 610, thecontroller/processor 659 implements the L2 layer for the user plane andthe control plane by providing header compression, ciphering, packetsegmentation and reordering, and multiplexing between logical andtransport channels based on radio resource allocations by the eNB 610.The controller/processor 659 is also responsible for HARQ operations,retransmission of lost packets, and signaling to the eNB 610.

Channel estimates derived by a channel estimator 658 from a referencesignal or feedback transmitted by the eNB 610 may be used by the TXprocessor 668 to select the appropriate coding and modulation schemes,and to facilitate spatial processing. The spatial streams generated bythe TX processor 668 are provided to different antenna 652 via separatetransmitters 654TX. Each transmitter 654TX modulates an RF carrier witha respective spatial stream for transmission.

The UL transmission is processed at the eNB 610 in a manner similar tothat described in connection with the receiver function at the UE 650.Each receiver 618RX receives a signal through its respective antenna620. Each receiver 618RX recovers information modulated onto an RFcarrier and provides the information to a RX processor 670. The RXprocessor 670 may implement the L1 layer.

The controller/processor 675 implements the L2 layer. Thecontroller/processor 675 can be associated with a memory 676 that storesprogram codes and data. The memory 676 may be referred to as acomputer-readable medium. In the UL, the controller/processor 675provides demultiplexing between transport and logical channels, packetreassembly, deciphering, header decompression, control signal processingto recover upper layer packets from the UE 650. Upper layer packets fromthe controller/processor 675 may be provided to the core network. Thecontroller/processor 675 is also responsible for error detection usingan ACK and/or NACK protocol to support HARQ operations. Thecontrollers/processors 675, 659 may direct the operations at the eNB 610and the UE 650, respectively.

The controller/processor 659 and/or other processors, components and/ormodules at the UE 650 may perform or direct operations, for example,operations 1100 in FIG. 11, operations 1400 in FIG. 14, and operations1700 in FIG. 17, and/or other processes for the techniques describedherein for optimizing VoLTE operations. In certain aspects, one or moreof any of the components shown in FIG. 6 may be employed to performexample operations 1100, operations 1400, operations 1700 and/or otherprocesses for the techniques described herein.

In certain aspects, the controller/processor 675 and/or otherprocessors, components and/or modules at the eNB 610 may perform ordirect operations, for example, operations 1000 in FIG. 10, operations1300 in FIG. 13, operations 1600 in FIG. 16, and/or other processes forthe techniques described herein for optimizing VoLTE operations. Incertain aspects, one or more of any of the components shown in FIG. 6may be employed to perform example operations 1000, operations 1300,operations 1600 and/or other processes for the techniques describedherein. The memories 660 and 676 may store data and program codes forthe UE 650 and eNB 610 respectively, accessible and executable by one ormore other components of the UE 650 and the eNB 610.

As mentioned above, one or more UEs in the wireless communicationnetwork (e.g., network 100) may be devices that have limitedcommunication resources, such as LC UEs, as compared to other (non-LC)devices in the wireless communication network.

In some systems, for example, in LTE Rel-13, the LC UE may be limited toa particular narrowband assignment (e.g., of no more than six resourceblocks (RBs)) within the available system bandwidth. However, the LC UEmay be able to re-tune (e.g., operate and/or camp) to differentnarrowband regions within the available system bandwidth of the LTEsystem, for example, in order to co-exist within the LTE system.

As another example of coexistence within the LTE system, LC UEs may beable to receive (with repetition) legacy physical broadcast channel(PBCH) (e.g., the LTE physical channel that, in general, carriesparameters that may be used for initial access to the cell) and supportone or more legacy physical random access channel (PRACH) formats. Forexample, the LC UE may be able to receive the legacy PBCH with one ormore additional repetitions of the PBCH across multiple subframes. Asanother example, the LC UE may be able to transmit one or morerepetitions of PRACH (e.g., with one or more PRACH formats supported) toan eNB in the LTE system. The PRACH may be used to identify the LC UE.Also, the number of repeated PRACH attempts may be configured by theeNB.

The LC UE may also be a link budget limited device and may operate indifferent modes of operation (e.g. entailing different amounts ofrepeated messages transmitted to or from the LC UE) based on its linkbudget limitation. For example, in some cases, the LC UE may operate ina normal coverage mode in which there is little to no repetition (e.g.,the amount of repetition needed for the UE to successfully receiveand/or transmit a message may be low or repetition may not even beneeded). Alternatively, in some cases, the LC UE may operate in acoverage enhancement (CE) mode in which there may be high amounts ofrepetition. For example, for a 328 bit payload, a LC UE in CE mode mayneed 150 or more repetitions of the payload in order to successfullyreceive the payload.

In some cases, e.g., also for LTE Rel-13, the LC UE may have limitedcapabilities with respect to its reception of broadcast and unicasttransmissions. For example, the maximum transport block (TB) size for abroadcast transmission received by the LC UE may be limited to 1000bits. Additionally, in some cases, the LC UE may not be able to receivemore than one unicast TB in a subframe. In some cases (e.g., for boththe CE mode and normal mode described above), the LC UE may not be ableto receive more than one broadcast TB in a subframe. Further, in somecases, the LC UE may not be able to receive both a unicast TB and abroadcast TB in a subframe.

For MTC, LC UEs that co-exist in the LTE system may also support newmessages for certain procedures, such as paging, random accessprocedure, etc. (e.g., as opposed to conventional messages used in LTEfor these procedures). In other words, these new messages for paging,random access procedure, etc. may be separate from the messages used forsimilar procedures associated with non-LC UEs. For example, as comparedto conventional paging messages used in LTE, LC UEs may be able tomonitor and/or receive paging messages that non-LC UEs may not be ableto monitor and/or receive. Similarly, as compared to conventional randomaccess response (RAR) messages used in a conventional random accessprocedure, LC UEs may be able to receive RAR messages that also may notbe able to be received by non-LC UEs. The new paging and RAR messagesassociated with LC UEs may also be repeated one or more times (e.g.,“bundled”). In addition, different numbers of repetitions (e.g.,different bundling sizes) for the new messages may be supported.

As mentioned above, MTC and/or eMTC operation may be supported in thewireless communication network (e.g., in coexistence with LTE or someother RAT). FIGS. 7A and 7B, for example, illustrate an example of howLC UEs in MTC operation may co-exist within a wideband system, such asLTE.

As illustrated in the example frame structure of FIG. 7A, subframesassociated with MTC and/or eMTC operation may be time divisionmultiplexed (TDM) with regular subframes associated with LTE (or someother RAT).

Additionally or alternatively, as illustrated in the example framestructure of FIG. 7B, one or more narrowband regions used by LC UEs inMTC may be frequency division multiplexed within the wider bandwidthsupported by LTE. Multiple narrowband regions, with each narrowbandregion spanning a bandwidth that is no greater than a total of 6 RBs,may be supported for MTC and/or eMTC operation. In some cases, each LCUE in MTC operation may operate within one narrowband region (e.g., at1.4 MHz or 6 RBs) at a time. However, LC UEs in MTC operation, at anygiven time, may re-tune to other narrowband regions in the wider systembandwidth. In some examples, multiple LC UEs may be served by the samenarrowband region. In other examples, multiple LC UEs may be served bydifferent narrowband regions (e.g., with each narrowband region spanning6 RBs). In yet other examples, different combinations of LC UEs may beserved by one or more same narrowband regions and/or one or moredifferent narrowband regions.

The LC UEs may operate (e.g., monitor/receive/transmit) within thenarrowband regions for various different operations. For example, asshown in FIG. 7B, a first narrowband region (e.g., spanning no more than6 RBs of the wideband data) of a subframe may be monitored by one ormore LC UEs for either a PSS, SSS, PBCH, MTC signaling, or pagingtransmission from a BS in the wireless communication network. As alsoshown in FIG. 7B, a second narrowband region (e.g., also spanning nomore than 6 RBs of the wideband data) of a subframe may be used by LCUEs to transmit a RACH or data previously configured in signalingreceived from a BS. In some cases, the second narrowband region may beutilized by the same LC UEs that utilized the first narrowband region(e.g., the LC UEs may have re-tuned to the second narrowband region totransmit after monitoring in the first narrowband region). In some cases(although not shown), the second narrowband region may be utilized bydifferent LC UEs than the LC UEs that utilized the first narrowbandregion.

Although the examples described herein assume a narrowband of 6 RBs,those skilled in the art will recognize that the techniques presentedherein may also be applied to different sizes of narrowband regions.

Certain networks, for example, such as long term evolution (LTE), may beInternet Protocol (IP)-based network that are packet-switched.Circuit-switched (CS) connections may not be supported in such networks.It may be desirable for voice calls and data to be carried on the sameLTE network. Voice over LTE (VoLTE) is a service for carrying voice anddata on LTE. In general, VoLTE employs a two state model, one state fortalking and one state for listening. As shown in FIG. 8A, for example,40% of a VoLTE call duration may be for talking, 40% of the VoLTE callduration may be for listening, and 20% of the call duration may besilent. Generally, during the talking state, a voice over IP (VoIP)packet is generated every 20 milliseconds (ms). The size of the packetmay depend on the voice encoder (vocoder) that is used by thetransmitting device. For example, for devices that use the adaptivemulti-rate (AMR) audio codec to encode at 12.2 kbit/s, the size of thepacket may be 31 bytes. During the listening state, the UE may generatea silence insertion descriptor (SID) packet every 160 ms. FIG. 8Billustrates an example of voice frames and SID frames. The SID packetmay be transmitted in order to keep the connection (e.g., for a VoLTEcall) alive. That is, the SID packet informs the device receiving thesilence frame that the transmitting device is still active andtransmitting during the call. Alternatively, or additionally, the SIDpacket may serve to generate a desired amount of background noise forthe call.

FIG. 8B shows one example exchange of voice frames and SID frames duringa VoLTE call, according to certain aspects of the present disclosure. Inthis example, while UE B is in the talking state, UE B transmits voiceframes 802 (e.g., in the uplink direction) to UE A (e.g., via eNB) every20 msec. Additionally, while in the talking state, UE B receives a SIDpacket 804 transmitted from UE A (e.g., via the eNB). Once UE Btransitions to the listening state, UE B receives UE A's voice frames802 (e.g., via the eNB) every 20 ms, and transmits a SID frame 804 to UEA (e.g., via the eNB) every 160 ms.

FIG. 9 illustrates an example talk+SID timeline 900 for an eMTC devicefor a portion of a VoLTE call, in accordance with certain aspects of thepresent disclosure. Timeline 900 includes a MAC bundling of two voiceframes 902, 904 (e.g., a duration of 40 ms) with DL talk frame 906 andUL Silence frame 908. DL talk frame 906 includes two downlinkrepetitions, and UL silence frame 902 includes 32 uplink repetitions.

In systems that support real time services, e.g., such as VoLTE, suchservices may have a strict latency budget in order to ensure a minimumlevel of voice quality for the VoIP call. However, as mentioned above,certain LC UEs (e.g., eMTC devices) may be link budget limited devicesoperating with limited communication resources (compared to other non-LCUEs in the network) that may make it difficult for such devices to meetthe strict latency budget for VoLTE operation. For example, in thedownlink direction, an eMTC device may be limited to 6 RBs. In somecases, the downlink limitation can be improved by power boosting at theeNB (e.g., ˜5 dB). For example, if PDSCH needs 20 resource blocks, thesame (or similar) link budget can be met by transmitting in 6 RBs, andpower boosting approximately 5.2 dB.

Still further, additional enhancements made in LTE Release 13 to supportMTC operations may make it difficult for eMTC devices to meet the strictlatency budget for VoLTE operation. For example, eMTC devices typicallyemploy half-duplex type B operation, which introduces retuning gapsbetween uplink and downlink directions. Thus, a UE that employs thistype of half-duplex operation may take one or more subframes to retune(or transition) from uplink to downlink and vice versa. FIG. 9, forexample, illustrates a single subframe (e.g., subframe 5) retuning gap910 from downlink to uplink. In this example, after the UE receives aphysical downlink shared channel (PDSCH) in subframe 4 of the firstradio frame 902A, the UE is not able to transmit physical uplink sharedchannel (PUSCH) until subframe 6 of the first radio frame 902A.

As another example, eMTC devices generally support cross-subframescheduling in the downlink. For example, a MTC physical downlink controlchannel (MPDCCH) received in subframe M may schedule PDSCH N subframesafter subframe M (e.g., in subframe M+N). As shown in FIG. 9, forexample, the MPDCCH received in subframe 1 of radio frame 902A schedulesPDSCH in subframe 3 of radio frame 902A (e.g., where N=2). Suchscheduling limitation can increase the control overhead, which limitsthe number of subframes that could have been used to receive data. Forexample, as shown in FIG. 9, the UE waits two subframes (where it cannotreceive) in order to receive a single subframe. Additionally, there maybe limited capacity of MPDCCH due to narrowband operation. For example,if the UE is monitoring for PDSCH in the entire narrowband (e.g., 6RBs), it may not be able to also monitor for MPDCCH. Other examples ofenhancements to eMTC that may affect VoLTE operation for eMTC devicesinclude reduced bandwidth, one receive (RX) antenna, non-support forslot-level hopping or distributed transmission (that would allow forfrequency diversity), etc.

In general, in order to achieve the strict link budget for VoLTEoperation, eMTC devices (or category M1 UEs) may have to support arepetition level (or bundling amount) of four in the downlink directionand a repetition level of thirty-two in the uplink direction (e.g., inorder to achieve a similar maximum coupling loss (MCL) as a category 1UE). However, due in part to cross subframe scheduling, it can bedifficult for eMTC devices to satisfy the link budget for VoLTEoperation. As shown in FIG. 9, for example, the timeline 900 supports abundling size of two for PDSCH as opposed to a bundling size of four.Note, however, that the above repetition levels for downlink and uplinkdirections assumes a bundling of two voice frames (e.g., a transmissionevery 40 ms). Those of ordinary skill in the art will recognize thatother repetition levels may be appropriate for other amounts of bundlingof voice frames.

Aspects presented herein provide techniques for optimizing VoLTEoperation for eMTC devices. Specifically, techniques presented hereinmay allow eMTC devices to more efficiently satisfy the link budgetassociated with VoLTE operation.

According to certain aspects, the BS may provide additional schedulingflexibility by setting some uplink subframes as invalid. In general, theBS can set a cell specific configuration of valid/invalid subframes forall UEs in the network. However, doing so may not be ideal in terms ofthe network resource utilization. Techniques, therefore, allow the BSand certain UEs (e.g., eMTC devices) to override the cell-specificconfiguration with a UE-specific configuration. Doing so may increasethe bundling size of the PDSCH, which in turn may give certain UEs moreflexibility to meet the link budget for VoLTE.

FIG. 10 is a flow diagram illustrating example operations 1000 forwireless communications, in accordance with certain aspects of thepresent disclosure. The operations 1000 may be performed, for example,by a BS (e.g., eNB 106, 610). The operations 1000 may begin, at 1002,where the BS determines a first configuration of one or more subframeswithin at least one radio frame available for a plurality of UEs to usefor bundled communications with the BS. At 1004, the BS determines, fora subset of the plurality of UEs, one or more subframes in the at leastone radio frame that are unavailable for bundled uplink transmissionsfrom the subset of UEs.

At 1006, the BS transmits an indication of the determined unavailablesubframes to the subset of UEs in order to override the firstconfiguration of subframes with a second configuration of one or moresubframes, within the at least one radio frame, for the subset of UEs touse for bundled communications with the BS. At 1008, the BS communicateswith the subset of UEs using the second configuration of subframes. Inone aspect, the communication with the subset of UEs may includeparticipating in a real time service (e.g., VoLTE call) with the subsetof UEs using the second configuration of subframes. For example, thetraffic received by the BS as part of the communication may include VoIPtraffic.

FIG. 11 is a flow diagram illustrating example operations 1100 forwireless communications, in accordance with certain aspects of thepresent disclosure. The operations 1100 may be performed, for example,by a UE (e.g., UE 102, 650, such as an MTC/eMTC UE or NB-IoT UE). Theoperations 1100 may begin, at 1102, where the UE determines a firstconfiguration of one or more subframes within at least one radio frameavailable for the UE and one or more other UEs to use for bundledcommunications with a BS. At 1104, the UE receives an indication of oneor more subframes within the at least one radio frame that areunavailable for bundled uplink transmissions by the UE.

At 1106, the UE determines a second configuration of one or moresubframes, within the at least one radio frame, for the UE to use forbundled communications with the BS based at least in part on thereceived indication. At 1108, the BS overrides the first configurationof subframes with the second configuration of one or more subframes. At1110, the UE communicates with the BS using the determined secondconfiguration of subframes. In one aspect, the communication with the BSmay include participating in a real time service with the BS.

In one aspect, the real time service may include a voice call that usesVoIP. In some cases, the voice call may have a strict latency budget toprovide good voice quality. The BS and/or UE may evaluate the quality ofthe voice call using one or more key performance indicators (KPIs) todetermine if the quality of the voice call is above a certain threshold(e.g., determine whether the strict latency budget is met). Someexamples of KPIs associated with the voice call include latency, jitter,packet loss, etc. The quality of the voice call may be inverselyproportional to the latency and jitter.

Alternatively, in one aspect, the BS and/or UE may be configured to usethe determined second configuration of subframes (e.g., forcommunication) based on determining that one or more performanceindicators associated with the voice call may not be met based on thefirst configuration of subframes. Such determination can be based onpredetermined metrics that indicate whether the performance indicatorsassociated with the voice call can be met based on the firstconfiguration of subframes. In one aspect, the BS and/or UE maydetermine the real time service to participate in based onidentification from at least one of a quality of service (QoS) classidentifier (QCI), an access point name (APN), Internet protocol (IP)address, differentiated services code point (DSCP) value, deep packetinspection, a static configuration for services or out of bandsignaling. Alternatively, in some cases, the eNB may already beparticipating in a VoIP call with a UE and may not determine the realtime service to participate using one of the above. Put differently, theeNB in some cases may bypass the above step. The out of band signalingmay be representative of the signaling between the LTE core and radionetwork components and the IMS components or between LTE core networkcomponents and the eNB.

In one aspect, the first configuration of subframes may be acell-specific configuration for all UEs in the network and may indicatethe valid/invalid subframes for the cell. In one aspect, the BS mayidentify a subset of UEs within the network and allow the identifiedsubset of UEs to override the first subframe configuration with a secondconfiguration of subframes (determined based on the indicated invalidsubframes for bundled uplink transmissions). In one aspect, the BS maydetermine the UEs in the subset based on the type (or capability) of theUEs. For example, the UEs in the subset may be Rel-14 UEs, and the otherUEs may be Rel-13 UEs (or support another release). In one example, thetype may correspond to bandwidth restricted UEs operating in a CE modeor power limited mode. In one example, the BS may determine whether theUEs are bandwidth restricted and operating in CE mode (or power limitedmode) based on one or more of a UE capability report, CQI, measurementreport from the UEs or a configured UE identifier. In some cases, the BSmay transmit the UE-specific parameter that indicates the overridingvalid/invalid subframe configuration (e.g., to the determined UEs in thesubset) via RRC configuration.

In one aspect, the BS may communicate (e.g., participate in a real-timeservice) with the subset of UEs by transmitting one or more bundleddownlink transmissions to the subset of UEs across multiple subframes.In one example, the multiple subframes in the radio frame (associatedwith the bundled downlink transmissions) may include at least one of theindicated unavailable subframes. The bundled downlink transmissions mayinclude repetitions of PDSCH.

According to certain aspects, the BS may introduce a delay bit (in agrant) to allow the subset of UEs to postpone (or delay) the start ofbundled uplink transmissions to the BS. That is, the BS may determine anamount of time for the subset of UEs to delay a start of bundled uplinktransmissions to the BS using the second configuration of subframes, andmay transmit an indication of the determined delay time to the subset ofUEs. In one aspect, the BS may transmit the delay within a grant of thebundled downlink transmissions to the UE. The BS can configure certaintypes of UEs (e.g., Rel 14 UEs) to monitor for the UL and/or DL grantswith the additional delay field.

Once the one or more UEs in the subset receive the indication of thesubframes that are unavailable for bundled uplink transmissions, thesubset of UEs may override the first configuration with a secondconfiguration determined based on the indication. In some cases, the UEsmay monitor for one or more bundled downlink transmissions from the BSacross multiple subframes including the at least one of the indicatedunavailable subframes. In one aspect, upon receiving the delayparameter, the UEs may determine a subframe in the at least one radioframe to start a bundled uplink transmission based on the indicatedamount of time to delay. The UEs may postpone the start of one or morebundled uplink transmissions scheduled to occur in one of the indicatedunavailable subframes until the determined subframe. The bundled uplinktransmissions may include one or more repetitions of PUSCH.

FIG. 12 shows one example of certain UEs (e.g., Rel 14 UEs) overriding acell-specific subframe configuration with a UE-specific subframeconfiguration in order to postpone PUSCH transmissions and allow formore repetitions for the PDSCH, in accordance with certain aspects ofthe present disclosure. The talk+SID timeline 1200 in FIG. 12 includes aMAC bundling of two voice frames 1202, 1204 (e.g., a duration of 40 ms)with DL talk frame 1206 and UL Silence frame 1208.

As shown, the UE (e.g., Rel 14 UE) receives an indication that subframes6 and 7 of radio frame 1202A are invalid subframes 1210 for UL. Inresponse, the UE postpones the start of the bundled UL silence frame(e.g., to subframe 8 of radio frame 1202A) and uses at least one of theinvalid subframes 1210 (subframe 6 of radio frame 1202A in this example)to monitor for additional PDSCH transmissions from the BS. In thismanner, the repetition level for PDSCH can be increased to four tosatisfy the link budget for VoLTE operation. For example, the DL talkframe 1206 includes four repetitions of PDSCH compared to DL talk frame906, which includes two repetitions of PDSCH.

According to certain aspects, techniques presented herein can increasescheduling flexibility by allowing devices to use a new “joint grant”that schedules both PDSCH and PUSCH at the same time. For example,certain UEs can be configured in a “joint grant” mode and monitor for agrant that contains assignments for both DL and UL shared channels.

FIG. 13 is a flow diagram illustrating example operations 1300 forwireless communications, in accordance with certain aspects of thepresent disclosure. The operations 1300 may be performed, for example,by a BS (e.g., eNB 106, 610). The operations 1300 may begin, at 1302,where the BS determines, for communications with a subset of a pluralityof UEs, a grant that schedules one or more bundled downlinktransmissions from the BS and one or more bundled uplink transmissionsfrom the subset of UEs. At 1304, the BS transmits the grant to thesubset of UEs in one subframe of a plurality of subframes within atleast one radio frame. At 1306, the BS communicates with the subset ofUEs based at least in part on the grant. In one aspect, thecommunication with the subset of UEs may include participating in a realtime service with the subset of UEs. The real time service may include avoice call using VoIP.

FIG. 14 is a flow diagram illustrating example operations 1400 forwireless communications, in accordance with certain aspects of thepresent disclosure. The operations 1400 may be performed, for example,by a UE (e.g., UE 102, 650, such as an eMTC device or NB-IoT device).The operations 1400 may begin, at 1402, where the UE receives, forcommunications with a BS, in one subframe of a plurality of subframeswithin at least one radio frame, a grant for bundled downlinktransmissions from the BS and bundled uplink transmissions from the UE.At 1404, the UE communicates with the BS based on the received grant.The communication with the BS may include participating in a real timeservice (e.g., a voice call using VoIP) with the BS.

According to certain aspects, the BS may configure certain types of UEsto monitor for the “joint grant” (e.g., “6-01” grant) that includes adownlink scheduling assignment (e.g., “6-1” format) and an uplinkscheduling grant (e.g., “6-0” format). In one aspect, the “joint grant”mode may be configured for devices that support a particular CE mode(e.g., CE mode A). The BS may configure the particular UEs to the “jointgrant” mode via RRC signaling.

In one aspect, the BS may configure two sets of grant parameters via RRCsignaling. In a first configuration, the BS may configure the UE for aninitial DL voice state and subsequent UL silence state. In a secondconfiguration, the BS may configure the UE for an initial UL voice stateand subsequent DL silence state. There may be a field in the “jointgrant” that indicates to the UE which configuration should be used forthe next transmission. The UE may transmit PUSCH a number of subframesafter the end of the PDSCH assignment. In one aspect, the UE maytransmit PUSCH two subframes after the end of the PDSCH assignment.

Once the UE is connected, the UE may monitor for the “joint grant.” Inone aspect, the UE may determine the bundle size for PUSCH and/or PDSCHimplicitly or explicitly from the RRC configuration or “joint grant.” Inone aspect, the “joint grant” may be aligned with the size of the uplinkscheduling grant (e.g., “6-0”) so as to not increase the number of blinddecodings. The “joint grant” may include information for at least one ofa resource allocation for a PUSCH, transport block (TB) size for thePUSCH, or bundling size for the PUSCH. Additionally, the “joint grant”may include information for at least one of a resource allocation for aPDSCH, TB size for the PDSCH, or bundling size for the PDSCH. The “jointgrant” may include one or two fields for the resource allocation (e.g.,to indicate the narrowband and/or number of RBs). Further, the set ofrepetitions may be different from previous sets. For example, in somecases, six repetitions (e.g., as opposed to four repetitions) may besupported in order to obtain an additional gain for the downlink.

FIG. 15 shows one example of certain UEs (e.g., Rel 14 UEs) monitoringfor a joint grant that contains PDSCH and PUSCH assignments, inaccordance with certain aspects of the present disclosure. The talk+SIDtimeline 1500 in FIG. 15 includes a MAC bundling of two voice frames1502, 1504 (e.g., a duration of 40 ms) with DL talk frame 1506 and ULSilence frame 1508. As shown, the UE (e.g., Rel 14 UE) receives a “jointgrant” 1510 that schedules both PDSCH and PUSCH at the same time (e.g.,in subframe 1 of radio frame 1502A). In this example, the repetitionlevel for PDSCH can also be increased to four to satisfy the link budgetfor VoLTE operation. For example, as shown, DL talk frame 1506 includesfour repetitions of PDSCH compared to DL talk frame 906, which includestwo repetitions of PDSCH.

As mentioned above, SID frames in VoLTE are generally used as keep-aliveframes (e.g., to indicate that the UE is still connected and has notlost coverage). However, in some cases, the BS can determine that the UEis still active based on detecting PUCCH (from the UE) transmitted inresponse to a PDSCH. For example, referring back to FIG. 9, in somecases, the UE may puncture one of the bundled PUSCH transmissions inorder to transmit a PUCCH 912. In such a case, it may not be necessaryfor UEs to transmit SID frames. Accordingly, techniques presented hereincan increase scheduling flexibility by allowing devices (e.g., UEs) toremove SID frames that are transmitted in the uplink direction andallowing devices (e.g., eNBs) to use the detection of PUCCH as analternative mechanism for keeping the connection alive.

According to certain aspects, when the BS detects PUCCH in response to aPDSCH, the PHY layer of the BS can send a message to the L2 layer of theBS indicating that the connection is alive (e.g., PUCCH was received,regardless of ACK/NAK). Once received, the L2 layer of the BS cangenerate an SID frame and send (or forward) the SID frame to higherlayers of the BS.

In one aspect, the HARQ engine of the eNB may also implement the abovetechnique. For example, when the HARQ engine receives an ACK, it mayflush the buffer and indicate to higher layers of the eNB that the ACKfor PUCCH was received. The higher layers, in turn, can generate andinsert the SID frame. Doing so in this manner can significantly increasethe downlink link budget (e.g., since PDSCH for voice can be repeatedmore often, and SID frames do not have to be transmitted in the uplink).

FIG. 16 is a flow diagram illustrating example operations 1600 forwireless communications, in accordance with certain aspects of thepresent disclosure. The operations 1600 may be performed, for example,by a BS (e.g., eNB 106, 610). The operations 1600 may begin, at 1602,where the BS receives, during communications with a UE, one or morebundled uplink transmissions from the UE without a SID frame. At 1604,the BS determines whether the bundled uplink transmissions include aPUCCH transmitted from the UE. At 1606, the BS decides whether tocontinue communicating with the UE based on the determination. In oneaspect, the communications with the UE may include participation in avoice call using VoIP.

According to one aspect, the BS may generate a SID frame for thecommunications (e.g., voice call) upon determining the bundled uplinktransmissions include a PUCCH. The BS may then deliver (or forward) theSID frame to one or more higher layers of the BS (e.g., to mimic thereception of the SID frame). In one aspect, the BS may decide tocontinue communicating with the UE if the BS determines the bundleduplink transmissions do include a PUCCH. In one aspect, the BS maydecide to discontinue communicating with the UE if the BS determines thebundled uplink transmissions do not include a PUCCH.

FIG. 17 is a flow diagram illustrating example operations 1700 forwireless communications, in accordance with certain aspects of thepresent disclosure. The operations 1700 may be performed, for example,by a UE (e.g., UE 102, 650, such as an eMTC device or NB-IoT device).The operations 1700 may begin, at 1702, where the UE transmits, duringcommunications with a BS, one or more bundled uplink transmissions tothe BS without a SID frame. At 1704, the UE transmits a PUCCH within thebundled uplink transmissions to indicate that the UE is connected to theBS via the communications. In one aspect, the communications with the BSmay include a voice call using VoIP.

In some aspects, the UE may transmit a PUCCH within a first one or morebundled uplink transmission to indicate the UE is connected to the BSvia the communications. In some aspects, the UE may transmit a secondone or more bundled uplink transmissions without a PUCCH to indicate theUE is not connected to the BS via the communications. In some cases, theUE may be a bandwidth restricted UE operating in a CE mode or powerlimited mode.

FIG. 18 illustrates an example talk+SID timeline 1800 for an eMTC devicefor a portion of a VoLTE call, in accordance with certain aspects of thepresent disclosure. Timeline 1800 includes a MAC bundling of four voiceframes 1802, 1804, 1806, 1808 (e.g., a duration of 80 ms). As shown inFIG. 18, in some aspects, the SID frame delivery may be delayed (e.g.,up to 50 ms). Once the UE transmits a scheduling request (SR) message1810, the UE may have to wait for the PUSCH assignment (in MPDCCH 1812)before it can begin transmitting the uplink silence frame 1814. Asshown, however, doing so extends the UL silence frame delivery, whichdelays the next DL voice frame 1816. However, by using one or more ofthe techniques described above, aspects presented herein may allowsubsequent frames to catch up to meet the deadlines associated withVoLTE.

The techniques described above VoLTE optimizations for eMTC devices mayhelp such devices satisfy the strict latency budget for VoLTEoperations.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover a, b, c,a-b, a-c, b-c, and a-b-c, as well as any combination with multiples ofthe same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b,b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c).Moreover, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” That is, unless specified otherwise, or clearfrom the context, the phrase “X employs A or B” is intended to mean anyof the natural inclusive permutations. That is, the phrase “X employs Aor B” is satisfied by any of the following instances: X employs A; Xemploys B; or X employs both A and B. In addition, the articles “a” and“an” as used in this application and the appended claims shouldgenerally be construed to mean “one or more” unless specified otherwiseor clear from the context to be directed to a singular form. As usedherein, including in the claims, the term “and/or,” when used in a listof two or more items, means that any one of the listed items can beemployed by itself, or any combination of two or more of the listeditems can be employed. For example, if a composition is described ascontaining components A, B, and/or C, the composition can contain Aalone; B alone; C alone; A and B in combination; A and C in combination;B and C in combination; or A, B, and C in combination.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

In some cases, rather than actually transmitting a frame, a device mayhave an interface to output a frame for transmission. For example, aprocessor may output a frame, via a bus interface, to an RF front endfor transmission. Similarly, rather than actually receiving a frame, adevice may have an interface to obtain a frame received from anotherdevice. For example, a processor may obtain (or receive) a frame, via abus interface, from an RF front end for transmission.

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software component(s)and/or module(s), including, but not limited to a circuit, anapplication specific integrated circuit (ASIC), or processor. Generally,where there are operations illustrated in figures, those operations mayhave corresponding counterpart means-plus-function components withsimilar numbering.

For example, means for determining, means for deciding, means forparticipating, means for evaluating, means for monitoring, means forgenerating, means for delivering, means for indicating, means foradjusting, means for establishing, means for delaying, means forallowing, means for identifying, means for overriding, means forpostponing, means for maintaining, means for communicating, means fortransmitting, means for forwarding, means for giving up, and/or meansfor including, may comprise a processing system, which may include oneor more processors, such as the TX processor 616, transmitter(s) 618,and/or the controller/processor 675 of the wireless base station 610illustrated in FIG. 6, and/or the TX processor 668, the transmitter(s)654, and/or the controller/processor 659 of the user equipment 650illustrated in FIG. 6. Means for transmitting, means for delivering,means for communicating, means for forwarding, and/or means for sendingmay comprise a transmitter, which may include TX processor 616,transmitter(s) 618, and/or the antenna(s) 620 of the wireless basestation 610 illustrated in FIG. 6, and/or the TX processor 668, thetransmitter(s) 654, and/or the antenna(s) 652 of the user equipment 650illustrated in FIG. 6. Means for receiving, means for forwarding, and/ormeans for communicating may comprise a receiver, which may include RXprocessor 670, receiver(s) 618, and/or the antenna(s) 620 of thewireless base station 610 illustrated in FIG. 6, and/or the RX processor656, the receiver(s) 654, and/or the antenna(s) 652 of the userequipment 650 illustrated in FIG. 6. In aspects, such means for mayinclude corresponding components of a network entity, such as an MME.

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device (PLD),discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

If implemented in hardware, an example hardware configuration maycomprise a processing system in a wireless node. The processing systemmay be implemented with a bus architecture. The bus may include anynumber of interconnecting buses and bridges depending on the specificapplication of the processing system and the overall design constraints.The bus may link together various circuits including a processor,machine-readable media, and a bus interface. The bus interface may beused to connect a network adapter, among other things, to the processingsystem via the bus. The network adapter may be used to implement thesignal processing functions of the PHY layer. In the case of a wirelessnode (e.g., see FIG. 1), a user interface (e.g., keypad, display, mouse,joystick, etc.) may also be connected to the bus. The bus may also linkvarious other circuits such as timing sources, peripherals, voltageregulators, power management circuits, and the like, which are wellknown in the art, and therefore, will not be described any further. Theprocessor may be implemented with one or more general-purpose and/orspecial-purpose processors. Examples include microprocessors,microcontrollers, DSP processors, and other circuitry that can executesoftware. Those skilled in the art will recognize how best to implementthe described functionality for the processing system depending on theparticular application and the overall design constraints imposed on theoverall system.

If implemented in software, the functions may be stored or transmittedover as one or more instructions or code on a computer-readable medium.Software shall be construed broadly to mean instructions, data, or anycombination thereof, whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Computer-readable media include both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. The processor may beresponsible for managing the bus and general processing, including theexecution of software modules stored on the machine-readable storagemedia. A computer-readable storage medium may be coupled to a processorsuch that the processor can read information from, and write informationto, the storage medium. In the alternative, the storage medium may beintegral to the processor. By way of example, the machine-readable mediamay include a transmission line, a carrier wave modulated by data,and/or a computer readable storage medium with instructions storedthereon separate from the wireless node, all of which may be accessed bythe processor through the bus interface. Alternatively, or in addition,the machine-readable media, or any portion thereof, may be integratedinto the processor, such as the case may be with cache and/or generalregister files. Examples of machine-readable storage media may include,by way of example, RAM (Random Access Memory), flash memory, phasechange memory, ROM (Read Only Memory), PROM (Programmable Read-OnlyMemory), EPROM (Erasable Programmable Read-Only Memory), EEPROM(Electrically Erasable Programmable Read-Only Memory), registers,magnetic disks, optical disks, hard drives, or any other suitablestorage medium, or any combination thereof. The machine-readable mediamay be embodied in a computer-program product.

A software module may comprise a single instruction, or manyinstructions, and may be distributed over several different codesegments, among different programs, and across multiple storage media.The computer-readable media may comprise a number of software modules.The software modules include instructions that, when executed by anapparatus such as a processor, cause the processing system to performvarious functions. The software modules may include a transmissionmodule and a receiving module. Each software module may reside in asingle storage device or be distributed across multiple storage devices.By way of example, a software module may be loaded into RAM from a harddrive when a triggering event occurs. During execution of the softwaremodule, the processor may load some of the instructions into cache toincrease access speed. One or more cache lines may then be loaded into ageneral register file for execution by the processor. When referring tothe functionality of a software module below, it will be understood thatsuch functionality is implemented by the processor when executinginstructions from that software module.

Also, any connection is properly termed a computer-readable medium. Forexample, if the software is transmitted from a website, server, or otherremote source using a coaxial cable, fiber optic cable, twisted pair,digital subscriber line (DSL), or wireless technologies such as infrared(IR), radio, and microwave, then the coaxial cable, fiber optic cable,twisted pair, DSL, or wireless technologies such as infrared, radio, andmicrowave are included in the definition of medium. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Thus, in some aspects computer-readable media maycomprise non-transitory computer-readable media (e.g., tangible media).In addition, for other aspects computer-readable media may comprisetransitory computer-readable media (e.g., a signal). Combinations of theabove should also be included within the scope of computer-readablemedia.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer-readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a wireless node and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a CD or DVD, etc.), such that a wireless node and/or basestation can obtain the various methods upon coupling or providing thestorage means to the device. Moreover, any other suitable technique forproviding the methods and techniques described herein to a device can beutilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

What is claimed is:
 1. A method for wireless communications by a basestation (BS), comprising: determining a first configuration of one ormore subframes within at least one radio frame available for a pluralityof user equipments (UEs) to use for bundled communications with the BS;determining, for a subset of the plurality of UEs, one or more subframesin the at least one radio frame that are unavailable for bundled uplinktransmissions from the subset of UEs; transmitting an indication of thedetermined unavailable one or more subframes to the subset of UEs tooverride the first configuration of subframes with a secondconfiguration of one or more subframes, within the at least one radioframe, for the subset of UEs to use for bundled communications with theBS; and communicating with the subset of UEs using the secondconfiguration of one or more subframes.
 2. The method of claim 1,further comprising: determining an amount of time for the subset of UEsto delay a start of bundled uplink transmissions to the BS using thesecond configuration of one or more subframes; and transmitting anindication of the determined amount of time to the subset of UEs.
 3. Themethod of claim 2, wherein communicating with the subset of UEs usingthe second configuration of one or more subframes comprises:transmitting one or more bundled downlink transmissions to the subset ofUEs across multiple subframes including at least one of the indicatedunavailable one or more subframes.
 4. The method of claim 3, wherein theindication of the determined amount of time is included within a grantof the bundled downlink transmissions transmitted by the BS.
 5. Themethod of claim 3, wherein the bundled downlink transmissions compriseone or more repetitions of a physical downlink shared channel (PDSCH).6. The method of claim 1, wherein communicating with the subset of UEsusing the second configuration of one or more subframes comprises:receiving one or more bundled uplink transmissions from the subset ofUEs across multiple subframes in the at least one radio frame, whereinthe bundled uplink transmissions comprise one or more repetitions of aphysical uplink shared channel (PUSCH).
 7. The method of claim 1,wherein communicating with the subset of UEs comprises participating ina real time service with the subset of UEs.
 8. The method of claim 7,wherein the real time service comprises a voice call using voice overInternet protocol (VoIP), and wherein traffic received by the BScomprises VoIP traffic.
 9. The method of claim 8, wherein the real timeservice is determined based on identification from at least one of aquality of service (QoS) class identifier (QCI), an access point name(APN), Internet protocol (IP) address, differentiated services codepoint (DSCP) value, deep packet inspection, a static configuration forservices, or out of band signaling.
 10. The method of claim 8, furthercomprising: evaluating one or more performance indicators for the voicecall to determine if quality of the voice call is above a threshold,wherein the one or more performance indicators comprise at least one ofa latency or a jitter for the voice call.
 11. The method of claim 10,wherein the quality of the voice call is inversely proportional to thelatency and the jitter.
 12. The method of claim 1, further comprising:determining the subset of UEs to communicate with based, at least inpart, on a type of the UEs in the subset.
 13. The method of claim 12,wherein the type of UEs in the subset comprise one or more bandwidthrestricted UEs operating in a coverage enhancement mode or power limitedmode.
 14. The method of claim 12, wherein the type of the UEs in thesubset is determined based on at least one of a UE capability report,channel quality indication (CQI), measurement report or a configured UEidentifier.
 15. An apparatus for wireless communications, comprising: atleast one processor configured to: determine a first configuration ofone or more subframes within at least one radio frame available for aplurality of user equipments (UEs) to use for bundled communicationswith the apparatus; determine, for a subset of the plurality of UEs, oneor more subframes in the at least one radio frame that are unavailablefor bundled uplink transmissions from the subset of UEs; transmit anindication of the determined unavailable one or more subframes to thesubset of UEs to override the first configuration of subframes with asecond configuration of one or more subframes, within the at least oneradio frame, for the subset of UEs to use for bundled communicationswith the apparatus; and communicate with the subset of UEs using thesecond configuration of one or more subframes; and a memory coupled tothe at least one processor.
 16. An apparatus for wirelesscommunications, comprising: means for determining a first configurationof one or more subframes within at least one radio frame available for aplurality of user equipments (UEs) to use for bundled communicationswith the apparatus; means for determining, for a subset of the pluralityof UEs, one or more subframes in the at least one radio frame that areunavailable for bundled uplink transmissions from the subset of UEs;means for transmitting an indication of the determined unavailable oneor more subframes to the subset of UEs to override the firstconfiguration of subframes with a second configuration of one or moresubframes, within the at least one radio frame, for the subset of UEs touse for bundled communications with the apparatus; and means forcommunicating with the subset of UEs using the second configuration ofone or more subframes.
 17. A non-transitory computer-readable medium forwireless communication by a base station (BS), the computer-readablemedium having computer executable code stored thereon, comprising: codefor determining a first configuration of one or more subframes within atleast one radio frame available for a plurality of user equipments (UEs)to use for bundled communications with the BS; code for determining, fora subset of the plurality of UEs, one or more subframes in the at leastone radio frame that are unavailable for bundled uplink transmissionsfrom the subset of UEs; code for transmitting an indication of thedetermined unavailable one or more subframes to the subset of UEs tooverride the first configuration of subframes with a secondconfiguration of one or more subframes, within the at least one radioframe, for the subset of UEs to use for bundled communications with theBS; and code for communicating with the subset of UEs using the secondconfiguration of one or more subframes.
 18. A method for wirelesscommunications by a user equipment (UE), comprising: determining a firstconfiguration of one or more subframes within at least one radio frameavailable for the UE and one or more other UEs to use for bundledcommunications with a base station (B S); receiving an indication of oneor more subframes within the at least one radio frame that areunavailable for bundled uplink transmissions by the UE; determining asecond configuration of one or more subframes, within the at least oneradio frame, for the UE to use for bundled communications with the BSbased at least in part on the received indication; overriding the firstconfiguration of subframes with the second configuration of one or moresubframes; and communicating with the BS using the determined secondconfiguration of one or more subframes.
 19. The method of claim 18,wherein the second configuration of one or more subframes comprises atleast one of the one or more subframes indicated as unavailable forbundled uplink transmissions.
 20. The method of claim 19, whereincommunicating with the BS using the determined second configuration ofone or more subframes comprises: monitoring for one or more bundleddownlink transmissions from the BS across multiple subframes includingthe at least one of the indicated unavailable one or more subframes. 21.The method of claim 20, wherein the bundled downlink transmissionscomprise one or more repetitions of a physical downlink shared channel(PDSCH).
 22. The method of claim 20, further comprising: determining,from a grant in one of the bundled downlink transmissions, an amount oftime to delay a start of one or more bundled uplink transmissions; anddetermining a subframe in the at least one radio frame to start abundled uplink transmission based on the amount of time to delay. 23.The method of claim 22, wherein communicating with the BS using thedetermined second configuration of one or more subframes furthercomprises: postponing a start of one or more bundled uplinktransmissions from the UE scheduled to occur in one of the indicatedunavailable one or more subframes until the determined subframe in theat least one radio frame.
 24. The method of claim 22, wherein thebundled uplink transmissions comprise one or more repetitions of aphysical uplink shared channel (PUSCH).
 25. The method of claim 18,wherein communicating with the BS comprises participating in a real timeservice with the BS.
 26. The method of claim 25, wherein the real timeservice comprises a voice call using voice over Internet protocol(VoIP).
 27. The method of claim 26, further comprising: evaluating oneor more performance indicators for the voice call to determine ifquality of the voice call is above a threshold, wherein the one or moreperformance indicators comprise at least one of a latency or a jitterfor the voice call.
 28. The method of claim 27, wherein the quality ofthe voice call is inversely proportional to the latency and the jitter.29. The method of claim 26, wherein the real time service is determinedbased on identification from at least one of a quality of service (QoS)class identifier (QCI), an access point name (APN), Internet protocol(IP) address, differentiated services code point (DSCP) value, deeppacket inspection, a static configuration for services, or out of bandsignaling.
 30. The method of claim 18, wherein the UE is a bandwidthrestricted UE operating in a coverage enhancement mode or power limitedmode.
 31. An apparatus for wireless communications, comprising: at leastone processor configured to: determine a first configuration of one ormore subframes within at least one radio frame available for theapparatus and one or more other apparatuses to use for bundledcommunications with a base station (BS); receive an indication of one ormore subframes within the at least one radio frame that are unavailablefor bundled uplink transmissions by the apparatus; determine a secondconfiguration of one or more subframes, within the at least one radioframe, for the apparatus to use for bundled communications with the BSbased at least in part on the received indication; override the firstconfiguration of subframes with the second configuration of one or moresubframes; and communicate with the BS using the determined secondconfiguration of one or more subframes; and a memory coupled to the atleast one processor.
 32. An apparatus for wireless communications,comprising: means for determining a first configuration of one or moresubframes within at least one radio frame available for the apparatusand one or more other apparatuses to use for bundled communications witha base station (BS); means for receiving an indication of one or moresubframes within the at least one radio frame that are unavailable forbundled uplink transmissions by the apparatus; means for determining asecond configuration of one or more subframes, within the at least oneradio frame, for the apparatus to use for bundled communications withthe BS based at least in part on the received indication; means foroverriding the first configuration of subframes with the secondconfiguration of one or more subframes; and means for communicating withthe BS using the determined second configuration of one or moresubframes.
 33. A non-transitory computer-readable medium for wirelesscommunication by a user equipment (UE), the computer-readable mediumhaving computer executable code stored thereon, comprising: code fordetermining a first configuration of one or more subframes within atleast one radio frame available for the UE and one or more other UEs touse for bundled communications with a base station (BS); code forreceiving an indication of one or more subframes within the at least oneradio frame that are unavailable for bundled uplink transmissions by theUE; code for determining a second configuration of one or moresubframes, within the at least one radio frame, for the UE to use forbundled communications with the BS based at least in part on thereceived indication; code for overriding the first configuration ofsubframes with the second configuration of one or more subframes; andcode for communicating with the BS using the determined secondconfiguration of one or more subframes.